Double slipper fluid pump



1955 H. c. LAZARUS DOUBLE SLIPPER FLUID PUMP 2 Sheets-Sheet 1 Filed June9, 1965 Nov. 8, 1966 H. c. LAZARUS 3,283,724

DOUBLE SLIPPER FLUID PUMP Filed June 9, 1965 2 Sheets-Sheet 2 zz fip w ZI 3,283,724 Patented Nov. 8, 1966 3,283,724 DOUBLE SUPPER FLUID PUMPHerbert C. Lazarus, Plymouth, Mich, assignor to The Ford Motor Company,Dear-born, Mich, a corporation of Delaware Fiied June 9, 1965, Ser. No.462,566 6 Claims. (Cl. 103-136) My invention relates generally topositive displacement fluid pumps. More particularly, it relates toimprovements in a slipper type pump having 'a driving rotor situatedrotatably within a pump housing which is ported suitably to accept fluidfrom a fluid reservoir and to deliver it under high pressure to a highpressure fluid delivery passage.

I am aware of conventional slipper type pump constructions having arotor with pumping cavities formed in its periphery. The rotor iseocentrically mounted for rotation within a pump chamber in the pumphousing. Slipper elements are situated loosely within the pump cavitieson the periphery of the rotor. The radially cutward surfaces of theslippers sealing-1y engage the inner peripheral surface of the pumpchamber.

Due to the eccentric position of the rotor with respect to the pumpchamber, the structure of my invention defines a series of segmentalpumping cavities that increase and decrease in size as the rotor isrotated through the pumping cycle. The housing can be ported suitabiy sothat the pumping cavities, as they increase in size, are in fluidcommunication with a fluid inlet port. Dining the portion of the pumpingcycle in which the pumping chambers decrease in size, the slippersestablish a fluid seal that prevents communication between the pumpingcavities and the inlet port. Communication is established at that time,however, with a high pressure delivery port.

In my improved pump construction, I have made provision for increasingthe volumetric capacity of a slipper pump arrangement for any givenrotor diameter. The improvements of my invention make it possible forthe pump construction to achieve a pressure ratio that exceeds thepressure ratio that may be obtained with a conventional slipper pumpconstruction of comparable size.

The provision of an improved pump construction of the type above setforth being a principal object of my invention, it is a further objectof my invention to provide a slipper pump having slipper pumpingelements that are arranged in pairs in peripherally disposed pumpingcavities formed in the periphery of the pump rotor. When the slippers ofmy improved structure are arranged in this fashion, the volumetriccapacity of each of the pumping cavities of the rotor progressivelydecreases as the individual cavities traverse the pumping arc. Duringthis portion of the operating cycle the slippers tend to move towardeach other. During the fluid intake portion of the operating cycle,however, the slippers tend to move tangentially away from each other.

It is another object of my invention to provide a positive displacementsliper pump of the type above set forth wherein spring means aredisposed between the individual slippers of each pair thereby resistingthe normal tendency of the slippers to move toward each other duringoperation as the slippers traverse the fluid intake are.

It is a further object of my invention to provide a positivedisplacement slipper pump of the type above set forth wherein theslipper elements establish an effective fluid seal on adjacent sealingsurfaces in the pumping arcs formed in the rotor. Provision is made alsoin my improved pump structure for establishing sealing engagement of theouter peripheries of the slippers on the circular internal diameter ofthe pump chamber formed in the pump body.

Further objects and features of my invention will become apparent fromthe following description and from the accompanying drawings, wherein:

FIGURE 1 shows in schema-tic form a fluid flow circuit that includes myimproved slipper pump construction;

FIGURE 2 shows in cross section an embodiment of my improved slipperpump construction; and

FIGURE 3 is an elevation view of the interior of the pump body shown inFIGURE -2.

In FIGURE 1, numeral 10 designates the pump body. It is formed with acylindrical pump chamber 12 within which is rotatably j'our-naled a pumprotor 14.

The pump chamber 12 is closed by a closure plate, not shown. A fluidpressure delivery port 16 formed in the body 10 extends arena-te ly influid communication with the chamber 12. It communicates also with thefluid. discharge conduit 18.

An arcuate fluid inlet port 20 also is formed in the body It) incommunication with the pumping chamber 12.

The rotor 14 is eccentrically positioned with respect to the geometriccenter of the cylindrical chamber 12. This creates a crescent shapedpumping cavity between the periphery of the rotor and the innercylindrical surface of the chamber 12. The ports 16 and 20 extendarcuately with respect to the center of the chamber 12.

A fluid return flow passage 22 communicates with the inlet port 20. Alsocommunicating with the inlet port 20 is a fluid supply passage 24 whichextends to a fluid reservoir identified by reference character 26.

The rotor 14, as viewed in FIGURES 1 and 2, rotates in acounterclockwise direction. Fluid is discharged through port 16 to ahydraulic apparatus 28 which responds to hydrostatic pressure. A flowreturn passage 30 interconnects the apparatus 28 with the sump orreservoir 26.

A bypass passage 32 communicates with passage 18. Communicating withthis passage 32 is a pressure relief valve 34 which is spring urged to abypass passage closing position. When the pressure in passage 32 reachesa predetermined value, the relief valve 34 will open thereby permittingby pass flow to enter the return passage 22. This pas-sage 22 terminatesin a nozzle which, by preference, directs fluid in the direction ofmotion of a point on the periphery of the rotor 14. The flow from thepassage 24 is combined with the flow from the nozzle at the end ofpassage 22 in a manner described in U. S. Patent No. 2,983,226.

The rotor 14 is powered by any suitable power source. If the pump isused with automotive accessories, the rotor 14 would be driven by meansof a suitable accessory torque delivery mechanism powered by the vehicleengme.

In FIGURE 2, I have illustrated more particularly the construction ofthe rotor and the slipper elements that are associated with it. Therotor is formed with a plurality of recesses 36 located on the peripheryof the rotor in the embodiment shown. There are eight such recesses atevenly spaced intervals. Situated between each recess is a sealingelement 38 having a sealing surface 49 which slidably engages thecylindrical surface of the opening 12 as an are between the trailingedge of the port 16 and the leading edge of the port 2% as seen inFIGURE 1.

Situated in each recess 36 is a pair of slipper pumping elements 42 and44. Element 42 is formed with a sealing surface 46 and a correspondingsealing surface 48 is formed on element 44. The surfaces 46 and 48engage respectively the juxtaposed sides of the recess 36.

A spring 50 is located between each pair of slipper pumping elements 42and 44. Each spring urges its companion slipper pumping elements intangential directions thereby tending to separate them. In this fashionsealing engagement is established between the surfaces 46 and 48 and theside surfaces of the recesses 36.

The radial thickness of the slipper elements 42 and 44. may be slightlyless than the radial depth of the recesses 36. The outer surfaces 52 and54 of the elements 42 and 44 are formed with a cylindrical shape whichcauses them to sealingly engage the cylindrical surface of the chamber12.

As the rotor 14 rotates in the direction of the arrow shown in FIGURES 1and 2, a slight wedging action is established by the slipper elements 44between the inner cylindrical surface of the chamber 12 and the adjacentsealing surface of the recess 36. This improves the sealing action atboth the surface 48 and the surface 54.

It will be apparent from an inspection of FIGURE 2 that the pumpingchambers 36 are in fluid communication with the intake port 20throughout a substantial arcuate extent. As each pair of slipperelements 42 and 44 traverse the arcuate extent of the intake port, theslipper elements 42 and 44 move radially outwardly thereby increasingthe volume of the cavities in the recesses 36 that communicate with theintake port. This increase in volume causes fluid to pass from theintake port into the recesses 36.

The bottom-dead-center position is shown in FIGURE 1. At that time oneslipper 42 of one recess 36 and the companion slipper element 44 of thenext preceding pair of slipper elements establish a seal between thetrai ing edge of the intake port 20 and the leading edge of thedischarge pressure port 16. As the rotor continues to rotate and eachcavity 36 passes the bottom-dead-center position, the volume of fluid ineach recess 36 is brought into communication with the discharge port 16.As each recess 36 traverses the arcuate extent of the discharge port itsvolume decreases progressively. This causes the fluid to be dischargedunder pressure into the discharge port. Pumping action continues untilthe pair of slipper elements approaches the top-dead-center position ofFIG- URE 2. When the individual pairs of slipper elements reach thetop-dead-center position, they again are effective to establish a sealbetween the high pressure discharge port and the low pressure intakeport. The seal, of course, can be supplemented also by the sealingeffect of the surface 40 on the rotor portion 38.

When I employ a slipper arrangement of this type, a larger volume offluid can be pumped for each revolution of the rotor of any given sizethan the corresponding volume of fluid that can be pumped with aconventional slipper pump of the type illustrated schematically, forexample, in US. Patent No. 2,983,226. In addition to the foregoing, theuse of separator springs between the individual pairs of pumpingelements reduces the tendency of the slipper elements to vibrate duringoperation, This tends to avoid a noise problem that is commonlyassociated with slipper pumps of this type. as a damper which prevents abuild-up in vibration forces.

The slipper elements themselves can be made of sintered iron if desired.Likewise the rotor can be made of sintered iron although it also can bemade of conventional materials and machined by means of sirnpl machiningtechniques in forming the recesses 36.

In a conventional slipper pump of the type generally indicated in PatentNo. 2,983,226, there is a limitation on the number of recesses that canbe formed in the periphery of the rotor. This, of course, reduces thepumping capacity. This limitation is avoided in my improved pumpconstruction since a larger portion of the peripheral region of therotor can be utilized for displacing fluid.

Having thus described a preferred embodiment of my invention, what Iclaim and desire to secure by U.S. Letters Patent is:

1. A positive displacement pump comprising a pump body, a pumpingchamber formed in said pump body, a rotor rotatably disposed in saidchamber, the axis of rota- The springs act tion of said rotor beingdisplaced from the geometric center of said chamber, a plurality ofrecesses formed in the periphery of said rotor, said recesses havingtangentially spaced sides that diverge radially outwardly with respectto each other, a pair of pumping elements movably mounted in each recesswhereby said pumping elements diverge as they move radially outward,said pumping elements sealingly engaging the peripheral wall of saidpumping chamber and adjacent sides of each recess, a pressure portcommunicating with said chamber and with each recess throughout asubstantial arcuate extent with respect to the geometric center of saidchamber, and a fluid supply port communicating with said chamber andwith said recesses at a location spaced arcuately from the location ofsaid pressure port.

2. A positive displacement slipper pump comprising a pump body, acircular pump chamber formed in said pump body, a cylindrical rotorrotatably journaled in said pump chamber for rotation about an axis thatis displaced from the geometric axis of said chamber, a plurality ofrecesses formed in the periphery of said rotor, said recesses havingtangentially spaced sides that diverge radially outwardly with respectto each other, said rotor and said pumping chamber cooperating to definea space of crescent shape, a fluid intake port communicating with saidspace throughout a substantial arcuate extent with one extremity thereofin proximity to the location of maximum radial thickness of saidcrescent shape space, a fluid pressure port communicating with saidcrescent shape space at a location spaced arcuately with respect to saidintake port, a pair of pumping slippers mounted in each recesses wherebysaid pumping slippers diverge as they move radially outward, theslippers having a radially outwardly curved surface sealinglyengageable' with the peripheral surface of said chamber, one side ofeach slipper sealingly engaging the adjacent side of its associatedrecess, the radially outward surface of one slipper of one recess andthe radially outward surface of another slipper of another recessestablishing a seal between the adjacent ends of each port.

3. A positive displacement slipper pump comprising a pump body, acylindrical pumping chamber formed in said pump body, a cylindricalrotor rotatably journaled in said pump chamber for rotation about anaxis that is displaced with respect to the geometric center of saidpumping chamber, a plurality of recesses formed in the periphery of saidrotor, said recesses having tangentially spaced sides that divergeradially outwardly with respect to each other, a pair of slipperelements disposed in each recess whereby said slipper elements divergeas they move radially outward, a fluid intake port located at onearcuate position in said pump body with respect to the geometric centerof said pumping chamber, a pressure port formed in said pump body influid communication with said chamber at a location arcuately spacedfrom said intake port, said recesses communicating with each portalternately as said rotor is rotated, said recesses receiving from saidintake port a volume of fluid as it traverses the arcuate extent of saidintake port, the volume of the fluid in said recess decreasingprogressively as said recess traverses the arcuate extent of saidpressure port, the radially inward region of each recess and itsassociated pair of slippers defining an individual fluid pumping chamberof variable volume, each slipper having a first sealing surfacesealingly engaging one side of its associated recess and another sealingsurface sealingly engaging the inner peripheral surface of said chamberwhereby each of said pumping chambers is isolated from an adjacentpumping chamber.

4. A positive displacement pump comprising a pump body, a pumpingchamber formed in said pump body, a cylindrical rotor rotatably disposedin said chamber, the axis of rotation of said rotor being displaced fromthe geometric center of said chamber, a plurality of segmental recessesformed in the periphery of said rotor, a pair of of each pair are urgedtangentially away from each other.

5. A positive displacement slipper pump comprising a pump body, a pumpchamber formed in said pump body, a cylindrical rotor rotatablyjournaled in said chamber for rotation about an axis that is displacedfrom the geometric axis of said chamber, a plurality of recesses formedin the periphery of said rotor, said rotor and said pumping chambercooperating to define a space therebetween the crescent shape, a fluidintake port communicating with said crescent shape space throughout asubstantial arcuate extent with one extremity of each port in proximityto a location of maximum radial thickness of said crescent shaped space,a fluid pressure port communicating with said crescent shape space at alocation spaced arcuately with respect to said intake port, a pair ofpumping slippers mounted in each recess, the slippers having a radiallyoutward curved surface sealingly engageable with the curved surface ofsaid chamber, one side of each slipper sealingly engaging the adjacentside of its associated recess, the radially outward surface of oneslipper of one recess and the radially outward surface of anotherslipper of another recess establishing a seal between the adjacent endsof said ports, and spring means situated between the slippers of eachpair whereby the slippers of each pair are urged tangentially away fromeach other.

6. A positive displacement slipper pump comprising a pump body, acylindrical pumping chamber formed in said pump body, a cylindricalrotor rotatably journalled in said pump chamber for rotation about anaxis that is displaced with respect to the geometric center of saidpumping chamber, a plurality of recesses formed in the periphery of saidrotor, a pair of slipper elements disposed in each recess, a fluidintake port located at one arcuate position in said pump body withrespect to the geometric center of said pumping chamber, a pressure portformed in said pump body in fluid communication with said chamber at alocation arcuate-1y spaced from said intake port, said recessescommunicatng with each port alternately as said rotor is rotated, saidrecesses receiving from said intake port a volume of fluid as ittraverses the arcuate extent of said intake port, the volume of thefluid in said recess decreasing progressively as said recess traversesthe arcuate extent of said pressure port, the radially inward region ofeach recess and its associated pair of slippers defining an individualfluid pumping chamber of variable volume, each slipper having a firstsealing surface sealingly engaging one side of its associated recess andanother sealing surface sealingly engaging the inner peripheral surfaceof said chamber whereby each of said pumping chambers is isolated froman adjacent pumping chamber, and spring means situated between theslippers of each pair whereby the slippers of each pair are urgedtangentially away from each other.

References Cited by the Examiner UNITED STATES PATENTS 2,974,603 3/1961Fraser 103-135 2,977,888 4/1961 Livermore 103-136 3,079,864 3/1963Drutchas et al. 103--135 MARK NEWMAN, Primary Examiner.

R. M. VARGO, Assistant Examiner.

1. A POSITIVE DISPLACEMENT PUMP COMPRISING A PUMP BODY, A PUMPINGCHAMBER FORMED IN SAID PUMP BODY, A ROTOR ROTATABLY DISPOSED IN SAIDCHAMBER, THE AXIS OF ROTATION OF SAID ROTOR BEING DISPLACED FROM THEGEOMETRIC CENTER OF SAID CHAMBER, A PLURALITY OF RECESSES FORMED IN THEPERIPHERY OF SAID ROTOR, SAID RECESSES HAVING TANGENTIALLY SPACED SIDESTHAT DIVERGE RADIALLY OUTWARDLY WITH RESPECT TO EACH OTHER, A PAIR OFPUMPING ELEMENTS MOVABLY MOUNTED IN EACH RECESS WHEREBY SAID PUMPINGELEMENTS DIVERGE AS THEY MOVE RADIALLY OUTWARD, SAID PUMPING ELEMENTSSEALINGLY ENGAGING THE PERIPHERAL WALL OF SAID PUMPING CHAMBER ANDADJACENT SIDES OF EACH RECESS, A PRESSURE PORT COMMUNICATING WITH SAIDCHAMBER AND WITH EACH RECESS THROUGHOUT A SUBSTANTIAL ARCUATE EXTENTWITH RESPECT TO THE GEOMETRIC CENTER OF SAID CHAMBER, AND A FLUID SUPPLYPORT COMMUNICATING WITH SAID CHAMBER AND WITH SAID RECESSES AT ALOCATION SPACED ARCUATELY FROM THE LOCATION OF SAID PRESSURE PORT.